1. Field of the Invention
The present invention relates to an apparatus for cutting a lateral wall of a pipe, and more particularly to an apparatus for cutting a lateral wall of a manhole (first pipe) to form a hole in the lateral wall of the manhole that is provided with an opening at which the manhole intersects and communicates with a sewer pipe or other main pipe (second pipe).
2. Description of the Related Art
In the prior art, a hole is formed in a lateral wall of a manhole around a sewer pipe connected to the manhole, and hard rubber or another elastic member is inserted into the resulting hole to make the main pipe quakeproof. To form the hole in the lateral wall of the manhole, for example, a cutter such as a drill is circularly rotated along the periphery of an opening in the manhole that communicates with the main pipe (JP-A-2002-227226).
A centering device may also be used to harmonize the axial center with the axial center of the main pipe, and a chainsaw or other cutter is used to cut the wall surface of the manhole (JP-A-2006-57390).
However, a problem of the method for drilling a hole in a lateral wall of a manhole in accordance with JP-A-2002-227226 is that it is difficult to position the rotational center of a drill, and a problem of the solution offered in JP-A-2006-57390 is that the components must be centered using a centering device.
Another drawback of both methods is that because a hole is drilled or cut with a metal drill or chainsaw, the lateral wall of the manhole may be broken or damaged in an unintended area, compromising the quakeproof properties of the manhole.